Color Blind Study
By Glen Haber
Every person inherits a set of chromosomes from each parent. The chromosomes that
determine the sex of the child are called ÒXÓ and ÒYÓ chromosomes, because of their shape.
All girls have two ÒXÓ chromosomes (XX), and all boys have one ÒXÓ and one ÒYÓ chromosome
(XY). When sex cells are created, the chromosomes separate. Every egg cell of a woman
contains one ÒXÓ chromosome. Half of a manÕs sperm cells contain one ÒXÓ chromosome, and
half of his sperm cells contain one ÒYÓ chromosome.
If the fatherÕs ÒXÓ chromosome is used to create a baby, the child will be a girl:
MotherÕs X + FatherÕs X = XX (female)
If the fatherÕs ÒYÓ chromosome is used to create a baby, the child will be a boy:
MotherÕs X + FatherÕs Y = XY (male)
Colorblindness is a sex-linked trait. It is caused by a gene that is located on
the ÒXÓ chromosome. The gene for colorblindness is not dominant. If a girl has one
colorblind ÒX, Ó she will not be colorblind, because she has another normal ÒXÓ chromosome.
She is called a carrier, because she can give the gene to her children, but she is not
If a man receives a colorblind ÒXÓ he will be colorblind. He has no other ÒXÓ
chromosome to overshadow the colorblind one, and the ÒYÓ chromosome has no gene for color
discrimination. When he has children, the colorblind man will give his ÒXÓ chromosome to
his daughters. Since his ÒXÓ has the colorblind gene, all of his daughters will be
carriers. The colorblind man contributes his ÒYÓ chromosome to make a son. Since the ÒYÓ
chromosome does not carry the colorblind gene, a colorblind man cannot give colorblindness
to a son.
The carrier female has one normal ÒXÓ and one colorblind ÒX.Ó Half of her eggs
will have a normal ÒXÓ chromosome, and half of her eggs will have a colorblind ÒX.Ó So
each time she has a baby, the child has a 50% chance of having the colorblind gene.
If the capital ÒXÓ represents the normal gene and the italic ÒxÓ represents the
colorblind gene, the possibilities would be as follows:
Normal female XX
Carrier female Xx
Colorblind female xx
Normal male XY
Colorblind male xY
RULES FOR PASSING THE COLORBLIND GENE:
1. A colorblind male cannot pass the gene to a son. If a boy is colorblind, he received
the gene from his mother.
2. A colorblind male will pass the gene to 100% of his daughters. Every daughter will
have at least one gene for colorblindness and will be capable of passing the gene to her
3. A male cannot be a carrier. If he has the gene for colorblindness, he will be
colorblind. If he is not colorblind, then he has no colorblind gene to pass to his
4. A colorblind female must have two genes for colorblindness- both ÒXÓ chromosomes must
carry the colorblindness gene. If a girl is colorblind, her father is also colorblind and
her mother is a carrier. Colorblind girls are very rare. No colorblind girls were found
in the DeKorne study.
5. A female carrier of colorblindness has a 50% chance of passing the colorblindness gene
to any given child. This does not mean that 50% of her children will be colorblind. Each
child has the same probability, and is independent of every other child. The carrier
could pass the gene to all or none of her children.
TRACKING THE COLORBLIND GENE
Tracking the gene began with Glen Haber, author of the study.
Glen is a 16-year-old colorblind male. Since a father cannot give colorblindness
to a son, GlenÕs mother Becky Bouwsma is a carrier.
A female can inherit the gene from either parent, so both of BeckyÕs parents are
considered. BeckyÕs father is not colorblind, so her mother, Rosemary Boerema, is a
carrier (much to her great surprise).
RosemaryÕs brothers, Don and John, are colorblind as well. Therefore, all of their
daughters are carriers: Barbara, Beverly, Bethany, Debby, Sandy, and Nancy Boerema.
Colorblindness showed up in the sons of the next generation.
RosemaryÓs brothers inherited the colorblind gene. Since fathers cannot pass the
gene to a son, John Boerema Sr. is not responsible. Nell DeKorne is the carrier.
Nell had four brothers and seven sisters. It would be very likely that some of her
siblings inherited the gene as well. If her father had been colorblind, all of the
daughters would have been carriers, and none of the sons would have been colorblind. If
her mother had been the carrier, the gene would be expected to show up in around half of
the children, but this would never be certain.
Several of the DeKorne descendants were contacted to try to determine the pattern
of inheritance. Here are the results reported by family.
1. Anna DeKorne Tigchon had one daughter, Trudy. Trudy reports no colorblindness in the
2. John DeKorne. Baldwin DeKorne and Jack DeKorne report that John DeKorne was not
3. Celia DeKorne Wierenga. CeliaÕs son Don Wierenga reports that he and brother Bud and
grandchild Emerson Schriener are colorblind. CeliaÕs great-grandson Brian Bechtel is
colorblind also. Mary Chleboun reports that Jon and Benjamin Chleboun are colorblind.
4. Nell DeKorne Boerema. Frankie Boerema and Beverly Veleber report that NellÕs
great-grandsons Todd Veleber, Troy Veleber, Ryan Brown, and Ben Caubel are all colorblind.
5. Lily DeKorne Thomasma. Marianne Orr, Susan Haughn, and Joyce Thomasma report no
colorblindness. Tom Thomasma reports that he is colorblind.
6. Ruby DeKorne Van Houten. Vera Van Houten reports that Randall Van Houten is mildly
7. Lewis DeKorne. Jack DeKorne and Baldwin DeKorne report that Lewis DeKorne was not
8. Casey DeKorne. Jack DeKorne and Baldwin DeKorne report that Casey DeKorne was not
9. Bertha DeKorne Peterson. Bill Peterson reports no colorblindness in the family.
Doug Crater reports that he is mildly colorblind.
10. Marguerite DeKorne Ryskamp. Ken Ryskamp reports that he and brother Jim are both
11. Mildred DeKorne died as an infant.
12. James DeKorne. Jane DeKorne and Baldwin DeKorne report that James DeKorne was not
Anna UNKNOWN John Normal Vision
Celia Carrier Lewis Normal Vision
Nell Carrier Casey Normal Vision
Lily Carrier James Normal Vision
Based on the information received about the boys, it is my theory that Boudewijn
DeKorne was colorblind. None of the sons are colorblind, which is what would be predicted
if the father had the gene. When the father is colorblind, all of the daughters become
carriers. Six of the eight girls are known carriers. The others could very likely be
carriers even in the absence of evidence.
The first unknown, Anna DeKorne, had one child, Trudy, who had a 50% chance of not
inheriting the gene. Trudy could easily beat the odds and still have a carrier mother.
The second unknown is Mildred. Since she died as a child, it can never be proven
if she was a genetic carrier
It may be that there are other DeKorne descendants that are so mildly colorblind that it
has little impact on their lives and they did not report it. Vera reported that Randall
Van Houten is not Òfully colorblind.Ó Glen Haber can see all colors, but has trouble
distinguishing blue and purple. Intense red, green, and brown are easy for him, but subtle
shades confuse him. On the other hand, Don Wierenga had more problems with color, and Ryan
Brown says he canÕt tell green from brown at all. Perhaps this range of colorblindness may
account for some underreporting.
The following list includes the reported colorblind descendants of Geertje and Boudewijn
Bud Wierenga, son of Celia DeKorne
Jon Chleboun, great-grandson of Celia DeKorne
Benjamin Chleboun, great-grandson of Celia DeKorne
Don Wierenga, son of Celia DeKorne
Emerson Schreiner, great-grandson of Celia DeKorne
Brian Bechtel, great-grandson of Celia DeKorne
Don Boerema, son of Nell DeKorne
Todd Veleber, great-grandson of Nell DeKorne
Troy Veleber, great-grandson of Nell DeKorne
John Boerema, son of Nell DeKorne
Ryan Brown, great-grandson of Nell DeKorne
Ben Caubel, great-grandson of Nell DeKorne
Glen Haber, great-grandson of Nell DeKorne
Tom Thomasma, son of Lily DeKorne
Randall Van Houten, son of Ruby DeKorne
Doug Crater, grandson of Bertha DeKorne
James Ryskamp, son of Marguerite DeKorne
Ken Ryskamp, son of Marguerite DeKorne
If a man is colorblind his mother and daughters are carriers. His daughters would all be
carriers, even if they did not actually have a colorblind son. Based on the colorblind
fathers and sons listed above, the following women all carried the colorblind gene:
Anna Dekorne Tigchon
Celia DeKorne Wierenga
Mary Beth Wierenga
Nell DeKorne Boerema
Lily DeKorne Thomasma
Ruby DeKorne Van Houten
Barbara Van Houten
Bertha DeKorne Peterson
Nancy Peterson Crater
Marguerite DeKorne Ryskamp
Any girl who can trace her female line directly back to a reported colorblind male or
known carrier has the potential to be a carrier, as the gene can be hidden in carriers for
generations. These possible carriers include:
This study will never be complete as more generations of colorblind sons will be born to
the current carriers. I welcome any additions and corrections to these lists, and any
information that could prove or refute my theory that Boudewijn DeKorne was colorblind. If
colorblindness could be traced to the descendants of Boudewijn DeKorneÕs siblings, Leuntje,
Cornelius, Marinus, and James, then it would be even more likely that Boudewijn was
colorblind. If, on the other hand, colorblindness could be discovered in Geertje RoestÕs
brothers or her Roest nephews, then the gene could be traced to the Roest family.
For additions, corrections, or outright denials, please contact Glen Haber at GLENBOLAKE@aol.com. Please do not write in purple.