Would rename Murderer to Bloodthirsty.
Would rename Anti-social to Asocial. Asocial avoids social interaction. Anti-social doesn’t, and he disregards the feelings and sensibilities of the present company.
The downside of Perfect Genes doesn’t make sense to me. Also, it might be overpowered regardless of downsides or point cost. It’s a sort of trait that would be impossible to balance.
Fat/Obese would interefe with basic logic with regards to food, eating and starvation, that is if you’re suggesting it to be a hard-coded trait that cannot be affected by eating or starving. I’ve thought about obesity too but not as a trait. Body mass index (BMI) would in my mind work like starvation, thirst, pain or sleep deprivation, but it should be slowest to change. Obesity or its opposite could inflict stat penalties. Also, even if BMI came to exist, it might be more of an annoyance, another aspect to control to maintain normal weight, unless perhaps being slim or slightly fat had their own upsides. On the other hand, I said it should be the slowest to change, so it might elude the realm of micromanagement. Another aspect of BMI to consider would be exercise, and that is not tracked at all.
But, OK, let’s say Fat would be a trait, we’d still have to explain it to separate it from hunger mechanism. Something like “Your body is naturally fat, and you are helpless to change that. Your metabolism is a formidable enemy… to you, that is. You almost get hungry and weak for even thinking about losing weight. That’s just the way you are. This is the weight your body and mind have accustomed to. But make no mistake, you are slower, your stamina drains faster, you are more prone to heart disease and your ankles hate you due to all the strain being placed on them, so you can’t carry as much. Being fat sure has its downsides - very dangerous and unpleasant downsides, especially now.”
Another option is to make a Fat character start out with like +100% obesity (akin to -80% starvation or thirst), and it would slooowly go down over time, let’s say in 100-150 days, regardless of food intake. During that time you would sustain various penalties, namely to max stamina, speed, and what else, and those penalties would go down slowly as well, until you’d be left with just the nullified Fat trait in your character sheet as a reminder. Obesity would be a one-time penalty, and couldn’t be affected.
Most importantly, before voicing any new traits, look at the existing ones and try to find some close matches, and reconsider. There are already a few almost identical traits, such as Padded Feet and Tough Feet. One must also consider the possibility of choosing several of these similar traits in character creation, and also consider appropriate exclusions. Which existing traits would Murderer/Bloodthirsty exclude? Or Weak Immune System? Or PETA Activist? Think things such as these through, and suggest exclusions as well, and in doing so discover the joys of crippling internal conflict as you struggle with your own ideas and counter-ideas. 