How to find age of a person?

I have just made a new friend at my kid’s school and have been racking my brains in an attempt to find out how old she actually is. I’d hate to ask her and lose a new friend. She looks about 25, but considering she has a teenage son, that just can’t be possible. There are various Excel and computer programs that apparently do help you to find the age of a person, if you know their birthday. However, they all seem pretty complicated to a tech ignoramus like me. But then I read that hands are a good indicator of a person’s age. The more lined they are, the greater the age. Well, in that case, my friend must be hitting her early 40’s but I sure don’t have the confidence to come out and ask her!