Warrior tribes have used many tactics in the past
When you have desirable traits, you are careful not to dilute your traits.
For example if you’re a slim and you can run fast and far. This could be very desirable if there isn’t a lot of food and you need a way to run to catch food.
It’s not desirable for somebody with those traits to meet with somebody who can dilute those traits.
I have identified groups that will introduce poisons into foods, these poisons cause you to gain weight. Making you obvious and destroying enzymes in your stomach causing you to stop receiving nourishment after you consume foods.
In essence you’ll become fat and begin starving at the same time. No matter what you do this warrior tribes continuously put poison in your food, to make your traits seem less desirable to others. For mating.
It could have to do with the fact that their tribe has fought against yours in the past.
And I want to deny you future children.
By making you seem less desirable for mating they can prevent you from spreading and multiplying.
You could have very dangerous traits to their tribe.