A blow to the groin is a good way for a child to create an opening so they can flee. It will not win the fight. A 12 year old can survive being attacked by an adult if they know to get away. One that tries to stand and fight will not.
In fact, particularly in Ying Wu Kwan, we are taught that what we are learning is not to actively seek out and win fights, it is to enable us to incapacitate an opponent long enough for us to flee- particularly if there are more than one of them, or if they seem especially fit and threatening.
A lot of martial I’ve seen actually don’t go for the groin as much, surprisingly, and I know that we don’t do that so often. However, to achieve a similar effect without having to strike an area that could potentially put you off balance of give them an opening, you might also go for the eyes or ears, or hit them a lot in rapid succession. This is because, after a certain amount of hits (generally about three) in a short period of time, they actually cannot count how much they have been hit. These strikes don’t need to be terribly hard either, as they’re not what takes them down.
But yeah.Unless the kid is the size and strength of an adult, and has enough fighting experience (actual fighting experience, not just training) then they are going to lose a fight if they actually try to take them on. A better solution would be to clap them on the ears, or wait for them to grab you, and use a technique to break the grab, and then break their wrist, and then run like fuck.
Yeah, that’s actually fairly standard self defense training. The basic idea is create an opening and get the hell out as fast as possible. The longer you stay in a fight, the greater the risk something goes horribly off the rails and you end up seriously injured or dead.