That’s a myth. Well. The suicide part. It was started because the normal lemming run wasn’t “dramatic” enough, and in any case, Lemmings don’t really run on cue, so Disney caught a bunch of lemmings and threw them over the cliff using a turntable for a white Wilderness (Like you know those spinning fertilizer or salt spreaders? It was like that. But with lemmings.)
Normally, lemmings make short hops to get down safely.
(Though for the record that was a really fun video game.)