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| If the human version is difficult, try using thoroughbreds: Silver Comic, Comic Strip , Now That's Funny, Red Ransom, and Silver Hawk Published by: The Courier-Journal (Louisville, KY, 20 Nov 1999, pg 20; newspapers.com. |
a3Genealogy Question Bag
Question: Are these first cousins as
I know them to be?
Answer: No, it appears you all are three-quarter siblings? This answer is so much easier to understand in thoroughbred horses!
In the a3Genealogy client's case, one man impregnated three sisters, and married two of them. The third sister married his first cousin. NEVER a dull moment at a3Genealogy and the In-Genes Team.
“Three-quarter siblings are siblings who are genetically half way between
full siblings and half siblings. This can happen, for example, if they share
the same father but different mothers but their mothers are sisters which makes
them effectively both half-siblings and first cousins. An alternative scenario
is if a woman has a child with both a man and his father which makes the
children related both as half-siblings and half-aunt/uncle vs
half-nephew/niece.
Three-quarter siblings
can occur as a result of the following scenarios:
·
a man has children with
each of two sisters (the children are related as half-siblings and first
cousins)
·
a woman has children by
each of two brothers (the children are related as half-siblings and first
cousins)
·
a woman has children with
both a man and his father (the children are related as half-siblings and
half-aunt or half-uncle and half-niece or half-nephew)
·
a man has children with
both a woman and her daughter (the children are related as half-siblings and
half-aunt or half-uncle and half-niece or half-nephew)
Full siblings share on
average 50% of their DNA when accounting for both fully identical and half-identical
regions. Three-quarter siblings share on average 37.5% of their DNA
with both full and half-identical regions.[1] However, the range of sharing for
both full siblings and three-quarter siblings is variable. Full siblings can
theoretically share between 38% and
61% of their DNA.[2] This means that there can be an
overlap in the ranges at the low end of sharing for full siblings and at the
high end of sharing for three-quarter siblings.”
Further Research
- Be sure to visit ISOGG WIKI
- What is a Three Quarter Sibling? from Wo Are You Made Of?
- 3/4 Siblings: You Can Tell the Difference by Brit Nicholson, 5 Aug 2021
- Relatedness: The Tech Interactive
Continue following the DNA for Genealogists Flipboard Magazine for articles like these. Articles of interest are constantly added.
Be Historically
Correct
Kathleen Brandt
a3genealogy.com
Accurate Accessible Answers
a3genealogy@gmail.com