At 14 yo, you can't. All "thinking" is self centered and emotional with a good dash of hormones (this is not a shot a females, it is also true for males), looking for acceptance. If you can't change the environment or pick their friends, they will push hard to do whatever it takes for acceptance in their group and adhere to those group norms.
Just make it very clear that you (strongly) disagree and then walk away.
At 14 yo, you can't. All "thinking" is self centered and emotional with a good dash of hormones (this is not a shot a females, it is also true for males), looking for acceptance. If you can't change the environment or pick their friends, they will push hard to do whatever it takes for acceptance in their group and adhere to those group norms.
Just make it very clear that you (strongly) disagree and then walk away.