Double first cousin
1656573
222463906
2008-06-29T13:51:02Z
WadeSimMiser
170099
Reverted edits by [[Special:Contributions/99.159.36.121|99.159.36.121]] to last version by Ward3001 (using [[WP:HG|Huggle]])
{{Unreferenced|date=May 2008}}
'''Double first cousins''' arise when two [[sibling]]s reproduce with another set of [[sibling]]s and the resulting children are related to each other through both [[parent]]s' families. Double first cousins share both sets of [[grandparent]]s in common and have double the degree of [[consanguinity]] than ordinary [[first cousin]]s. Genetically they are as related as [[sibling#Half sibling|half-siblings]]. Their coefficient of coancestry is 1/8th or 0.125. While double first cousins have the same coefficient of coancestry (1/8) as half-siblings, they do have higher chances of sharing ''both'' alleles (1/16 vs 0) and lower chances of sharing one allele (3/8 vs 1/2) with each other than half-siblings.
When [[identical twin]]s reproduce with identical twins (or identical twins reproduce with the same person) the resulting children are genetically indistinguishable from full siblings. When identical twins reproduce with siblings the resulting children are more related than half-siblings but less related than full siblings.
Children of double first cousins are double second cousins.
==See also==
*[[Parallel cousin]]
[[Category:Biology]]
[[Category:Kinship and descent]]
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