"in one family, a son was born with polydactyly toes while his sister had polydactyly fingers. in explaining this phenomenon in genetic terms to the parents, which concept should be addressed? "

The answer is " Variable expressivity of a gene".

Having an additional finger or toe is called polydactyly. The additional digit may go from a little, raised knock to an entire, working finger or toe. More often than not, it's littler than alternate digits and not very much framed.