Teaching kid not to follow the crowd

I've got two stubborn kids, who can be relied on *not* to do something
just because everyone else does.

The other kid is showing strong tendancies of following the crowd. We
are concened about this - for instance today It was insistant that
because Sibling had told It to "get lost" during an argument, It had
to go out and get lost, to the extent of leaving the house complete with
pocket money.

The child in question is about 8yo, but we are thinking ahead to the
teenage years.

If we asked It whether they would jump off a bridge just because
everyone else did, I think if they were in a stroppy mood, they would
say yes.

Does anyone have any suggestions as to how we can get them to resist
peer pressure when appropriate? We have several years before it gets
to be a serious issue, but I'd like to lay the groundwork now.

--
Penny Gaines
UK mum to three