How do they make multi-trunk palms?

I see so many multi-trunked palms that I know do not start their natural lives that way. Does anyone know the "secret" to how it is done?

Thanks!

They plant three seedlings close together when the plants are small and let them grow that way.Then there are clumping palms like Chamerops and so of the windmill types. Fishtail palms usually clump on their own too.Many exceptions to this rule.