1) Mary has a widow's peak (either WW or Ww), but her sister has a smooth hairline (must be ww). Is either one of Mary's parents homozygous dominant or recessive? I think that that she has to have at least one of her two parents be homozygous something in order for this to work?

Question

1)  Mary has a widow's peak (either WW or Ww), but her sister has a smooth hairline (must be ww).  Is either one of Mary's parents homozygous dominant or recessive?  I think that that she has to have at least one of her two parents be homozygous something in order for this to work?

PsyDAG · Answer

Since sister is ww, must have received w from each parent. Both parents would be Ww or one Ww and the other ww.. Try a punnett square.

https://www.google.com/search?client=safari&rls=en&q=punnett+square&ie=UTF-8&oe=UTF-8