Is lactose intolerance a dominant or a recessive gene?
All humans are born lactose tolerant, which means everyone can make the enzyme that
breaks up lactose. This is because babies need mother’s milk.
Once a baby (or any mammal, like a puppy for instance) is weaned, it no longer needs
to produce the enzyme that helps digesting lactose, because milk is the only natural
source of lactose.
The “gene” for lactose intolerance is just a controlling region programmed to shut down
the enzyme production around age four.
As most people continue to consume milk, our bodies keep producing the lactose breaking
However lactose intolerance can occur at any moment in one’s lifetime as the body can
shut down the enzyme production anytime.