Lactose - Friend or Foe?

Today someone at work brought in a huge chocolate cake and put it in the kitchen. I forgot to bring breakfast to work and the chocolate cake was calling me. So I decided to have some for breakfast (not very sparkle-y of me) but I would have to have a glass of milk with it. So I took the milk out of the fridge and someone in the kitchen asked if I was planning to have a glass of milk. I said, yes, I need it to go with the cake. She said that I was the only Jewish person she knew who was not lactose intolerant. But then she asked me how old I was. I told her I was half way through a deck of cards (26) and she said, oh. It hit everyone I knew in their late 20's and 30's. She said in her 20's she was all about cheese and milk. I said... hmm, my siblings claim they're lactose intolerant. Maybe it is something that hits you later in life. I know lots of people become lactose intolerant after they stop drinking breast milk, but I guess I always thought that if you were in your 20's and fine with lactose you were good to go. Lactose was your friend, an ally.
So the question becomes: Is my time with lactose limited?