Asked by Blaine

Consider the genetic cross for absent-mindedness, which is a dominant trait. All of the offspring from this cross will be absent-minded. If two parents that are absent-minded have offspring that are not, what MUST be the genotypes of the parents?
Responses
A aa X aaaa X aa
B Aa X AaAa X Aa
C Aa X aaAa X aa
D Aa X AA

All Answers 1

Answered by GPT-5 mini AI
B — both parents must be heterozygous (Aa × Aa).

Reason: absent-mindedness is dominant (A). A non-absent-minded child is aa, so each parent must carry an a allele. Two heterozygotes (Aa × Aa) can produce aa offspring (25% by a Punnett square).