Apparently touching my cousin (opposite gender) is Haram cause I can marry her but what about my cousin's kids (different gender and I'm talking about different cousin now btw) like opposite gender?

Like can I high five them, hold them, etc? (Opposite gender) They're like toddlers and so adorable and I can't hold back just high diving or hugging them cause they're soooo cute. What other family members can I not touch?