Which is worse, if one can be said to be worse than the other? Is it worse for a woman to have sex with her daughter’s husband than for a man to have sex with his brother’s wife? Are these equally reprehensible? Is neither a big deal? Who do you really blame in these scenarios?
I frankly think it’s worse for a woman to have sex with her daughter’s husband. I mean, that’s your daughter. Brothers and sisters have no real duty to each other just for being brother and sister, but parents do have a moral duty towards their children. I get that some parents accept no such moral duty, and technically speaking they don’t have to. Some mothers compete with their daughters and consciously and intentionally set out to harm their daughters. Some might not intentionally set out to harm their daughters but they won’t deprive themselves of their own wants and needs for their daughters’ sakes, even if what they want and think they need is to have sex with their daughters’ husbands.
Siblings don’t owe each other anything. It’s nice when siblings look out for each other and consider each other someone they love and would never hurt in any way; but sibling rivalry is fairly common. A man sleeping with his brother’s wife is just a man who slept with another man’s wife. The brother element hardly factors into the equation.
In most cases a man who would sleep with his brother’s wife does not have a close relationship with his brother to begin with. A man who has a close relationship with his brother is less likely to risk that relationship for the pleasure of a woman’s sex. He might be attracted to his brother’s wife but he isn’t usually going to pursue her and sleep with her because his relationship with his brother is going to come first.
In both scenarios it’s highly unlikely that the woman who sleeps with her daughter’s husband and the man who sleeps with his brothers wife have close, loving relationships with the individuals they wrong by their actions.