My six year old still re-hashes the day she got stitches. She was all of two and one-half when she and her dad were goofing around. She fell and following in my foot steps needed stitches on her chin. When she's annoyed or angry, or just in need of something to say, she will bring up this incident.
She's got a mind like a steel trap.
She's not going to forget. Ever. It's like living with a talkative elephant. It doesn't matter if it happened four years ago or four minutes ago, she remembers. Unless of course you just asked her to be quiet. That request is forgotten even before it passes through her synapses.
Boys hit. It's that simple.
Are you in his face? He's going to hit you.
Did you take his snack? He's going to hit you.
You are hovering? Smack.
You called him a name? Thwap.
You were just sitting there doing absolutely nothing? (code for sticking your tongue out) Yep, that earns a smack.
You are breathing. Smack.
Boys hit and that's the end.
Until it's time to hit a girl...again.
Girls will still be penalizing their brothers for hitting them when they were five, twenty years later.
Just for the record, my admonitions of "We don't hit girls!" have been met by "She's not a girl, she's my sister." Yes, I have some training to do.