Family trees and sex determination

• Polydactyly is an inherited condition in which a person develops an extra finger

  or toe and it is determined by a dominant allele

  The three genotypes are:

  DD: person has polydactyly

  Dd: Person has polydactyly

  dd: person has normal number of digits
• Our sex, whether we are male or female, is determined by the X and Y

  chromosomes – the sex chromosomes.
• A woman has two X chromosomes and a man has one X and one Y

  chromosome
• Inheritance of sex can be determined using a genetic diagram