system
Given the following post, respond as if you're commenting on Reddit:
human
Am I more closely related to my sister or my mother?

My sister and I both have genes from both my mother and father, whilst my mother only has shared genes with me and my sister, and none from my father (if she did that would be a bit weird). Who is more closely related, my mother and I or my sister and I?
gpt
Ignoring the X and Y chromosomes, you get exactly half of your DNA from your father and half from your mother.  The sperm contains half a set of chromosomes and the egg contains the other half.

Comparing against a sibling, you have a 50% chance of getting the same copy of any given gene from your father since he has two versions you each can get.  Same goes for the copy from your mother.  Each is approximately a coin flip, although the genes on a particular chromosome tend to go together so you're more likely to have all the same or all different.

The net result is that on average you're related to a sibling as much as you are related to your parent, but there's more variance in your relatedness to siblings.