Things don't have single causes. That's what's retarded about modern science. Take things out of a world with infinite causes and stick it in a simulated environment, then act like you found something.

If I stab you, did knife, the wound, gravity, air pressure, arterial pressure, evolution, anger, or economic reasons cause you to die? It depends on who you ask. A person doing a race study will have a very different answer than a cardiologist or a paleontologist.

Sex is the problem and the solution. Multiple partners is unhealthy. Simple as.