I guess just like many plants I've seen and not only my houseplants with light comming in sideways from the brightest light source, even some outdoors, if in shade will lean towards the brightest direction the sun is comming from, so I'd guess that could be the reason for some palms not growing straight, though I've seen pictures with some in full sun evidently , that curve or lean as well. In that case however, it's possible that prevailing winds in one direction will bend those palms as they grow. As for the ones that seem to start growing first in one direction and then sort of turn later on as they've grown, that's a bit more difficult to explain. However, that light thing for indoor growing is one reason , that perhaps palms, as any other indoor plant should be rotated frequently, so they grow a bit straighter and don't lean so much. With the tight quarters mine have however, I rarely find it practical to turn them frequently.

I have thought that too bird but what about island palms like cocos for example have you ever seen them all
curve in the same way ?
What i mean by that is if you take several cocos put them in a straight line and plant them exactly a like...in a few years later come back to look at them you'll notice some curve... some don't thats my question... why ?
You would think the sun hits them all evenly wouldn't you ?

No more insight .....
come on guys !

They are attracted to the light. Light makes the plant move around. When plants grow under other plants, they either must move to get the light or stay small. The strong shall inherit the earth.

When I was in Jamaica last Feb, I walked through coco palm plantation up a hill and well away from the shore, with a non-sandy soil. Every single palm was straight, vertical, not a single curved trunk

Down on the sandy beach, the palms were erect, leaning in many directions, curved more or less, some even flat along the ground before turning upward again.

I figured they beach palms had been blown around by strong winds and/or the sand soaked at very high tides/surf, sand being not the most stable platform even when dry.