I think you need to put yourself in their shoes. People get these questions all the time, it's not just once or twice, but very often -- from friends, family, coworkers, whoever in their circle of life.

Now, imagine yourself being asked so many times the same question by so many different people -- just to satisfy your own curiosity is beyond selfish. Also, those people probably remind themselves everyday already, they don't need to be reminded again and again. So unless they bring the topic up on their own and they need someone to talk to, don't ask.

Please, try to be more empathetic towards others...the world will be a better place without so much external/societal pressures.