Approximately 20% of the world’s adult population are able to digest milk sugar (lactose).They are “lactose tolerant.” This trait is known to be controlled by a single dominant gene. Therefore, we would expect that no lactose tolerant individuals have two biological parents that are lactose INtolerant.

all lactose tolerant individuals to be heterozygous for the gene.

60% of lactose INtolerant individuals would be heterozygous.

all children of lactose tolerant parents will also be lactose tolerant.