Dear Rabbi Simon,
What is the meaning of peyos? I know that traditionally chassidic and yeminite Jewish men grow their sidelocks, but it seems to have become 'de rigueur' in the wider charedi world, Ashkenazi and Sephardi alike; not everyone of course, like yourself and your sons. However, I have seen young boys with peyos but their fathers without, which I find even more confusing.
Thank you for clarifying, Philippe
The Torah says (Lev. 19:27) "do not round (that is, shave) the corners (pe’ot) of your scalp." The "corners" are understood to be the area of the face in front of one's ears, ie the sideburns. Specifically, the sideburns must extend to the point where the jawbone moves when you open your mouth. Put your finger in front of your earlobe and open your mouth wide and you will see (or feel) what I mean. This prohibition is applicable to men and not women, as it is connected to the prohibition of shaving the beard (with a razor blade). Since men have beards and women do not, the law of peyot is also applicable to men but does not restrict women (in principle).
So much for the prohibition. In some circles, especially those influenced by kabbalistic teachings, it has become commonplace to accentuate that which the Torah forbids removing completely. (For reasons which are not clear to me, Lubavitch hassidim do not follow this practice.) This has the effect of creating a "Jewish" look–though some choose to (partially) hide their peyot under a kippah or hat, or trim them and comb them behind the ears.
Children often have peyot because of the related minhag of not cutting a boy's hair until he is three, and then leaving his peyot at that time (and subsequently).
My rebbeim did not have peyot, nor was it the norm in the Lithuanian yeshivot. However peyot are becoming increasingly popular, and widespread, as ethnic dressing becomes acceptable and even fashionable, particularly in the Jewish world. IMO there are legitimate grounds on which to both support and critique this trend. We are fortunate to live in a time and in a place where one can choose the path that works best for him.