237: Desire to change others, Sibling concerns, Step-dad harsh with stepson

1. If it is true that we can't change people, why would evolution waste energy engineer feelings in us that make us feel incline to try to change others? If we can't change others, why do people come to believe they can or enter relationships with others on that premise? 2. My brother has always been very private about his relationship with his significant other, to the point that it makes our family uncomfortable.  She was a foreign exchange student when they met, failed to meet requirements for her work visa this spring, and my brother finally told us they got married this past May to keep her in the states. He also expressed as recently as one year ago he is not even sure he likes her, but does enjoy her attention and having company. I guess my question here is twofold; is it worth expressing concern to him about this being that's it's done? It was a particularly hard blow to my parents, who are practicing Catholics, and I don't see how he could fail to see the hurt it would cause them. Second... from a gene standpoint, why did he do this? 3. I have a 15 year old son who did poorly in school after it moved online last spring - eventually he stopped doing any of his work and lied to my husband and I about it. He is returning to a hybrid model in a couple of weeks, and I am already dreading the acrimony that will follow. My husband is our son's stepfather with no biological children of his own. In the past, there has been conflict between my husband and I about how to handle this - I think my husband is draconian and he thinks I'm too relaxed. How much freedom is appropriate to give kids when it comes to schoolwork? What about lying? Is there any way to protect my relationships with both my husband and my son through this? And finally, why do some step-parents (like my husband) get so invested in kids that will not be carrying their genes forward?