Why are some girls jigglier than others?

[Luna Hellborn CLIPS]

I confirm what they said! 
I'll give you the example of me and my sister: we're the same height but she weighs 50kg, I weigh 80+kg
But she shakes like a pudding whatever movement she makes, while my skin is tight and my fat extremely firm and to jiggle I have to jump and shake a lot 😅
I want a soft ass to shake with slaps.. 😭

[Luna Hellborn CLIPS]

I think it depends on several factors, underlying musculature, genetics and skin "texture". 
I don't play sports, while my sister plays tennis regularly, but her skin is thinner and softer than mine, if you pinch it you can "get" it between your fingers while mine is super elastic and firm and you can't pinch it. Technically I should be the one wobbling like a pudding, not her. 

Another factor to take into consideration is if there has been any weight loss leading to "drained" skin that makes even very thin former obese girls shaky.

I hope I have expressed myself correctly!