Sibling rivalry: what’s normal?

[Mummutum]

I’ve got two DC, 6 (boy) and 2.5 (girl). DS wasnt especially interested in his sister when she was born but around her first birthday they started to have fun. Now they play together loads, he likes to teach her things but she also has her own will and they’ll do pretend games together (toy kitchen, playing with pillows and tents and such, running outside). Although she will also follow him around when he’s not keen and annoy him.

I didn’t grow up with a close sibling, what’s a normal amount of conflict and quarrelling? What might signify we need to intervene (besides obvious things like hitting or hurting each other, but even then I don’t know, should I let them try to sort it themselves if DD is blowing raspberries and DS is saying to leave him alone but she’s ignoring him?)

What you describe isn't really sibling rivalry, more just annoying each other.

You should teach both your children to respect other people's personal space. They should both be taught (at an age appropriate level) that stop/no means stop/no and they are to stop when they hear it. It's not even about siblings it's about them growing up to to be decent people.

So in conclusion, you need to tell DD to stop because that's what we do (always) when someone asks us to stop being in their physical space.