Every person is unique. People get the quirks from their parents, and their parents before them. Brining us to the reason people are different is because of the culture they are from. The longer a family is in a new place the more assimilated they can become, but if they stick to their roots the thing that you think is weird or annoying might really be what makes that individual so special.
Below is a link to an article discussing cultural norms and whether or not they matter.