sentences: one parent is the source of 50% of the genes in a fertilized egg through sexual reproduction
docs: pollination is fertilization. offspring is product_of_sexual_activity. sexual_reproduction is reproduction. sex is primarily_for_procreation. biological_father is parent. stratifying is reproductive_fertilization. biological_mother is parent. genetic_marker is gene. egg_fertilization is reproductive_fertilization. sexual_reproduction is biological_reproduction.