Two tongue-rollers have 12 children. 8 of their children can roll their tongues and 4 cannot. Make an argument about the genotype of each of the parents and use a punnett square to explain your reasoning.

Let the dominant gene for tongue rolling be R while the receive gene be r. Therefore the genotype of the parent is heterogeneous that Rr x Rr since they are having children who are not able to roll the tongue. The punnet square is as follows.

If capital T is dominant trait of tongue-rolling, then little t is recessive trait of no-tongue rolling. For 8 children to roll their tongues (TT or Tt) and 4 children who can't (tt) both parents must be heterozygous (Tt).