In a new study of 280 people, researchers found that a measure of feminized brain structure (i.e., 2D:4D digit ratio) was associated with less distress at the hypothetical scenario of sexual as opposed to emotional infidelity by an intimate partner. The relationship was observed for men and women together, but not for each group individually. This relationship for the combined groups disappeared when gender was controlled. This supports the conclusion that males's higher level of prenatal testosterone masculinizes their brains making them more focused than females on sexual infidelity. Men are thought to be more sensitive than women to cues of sexual infidelity to prevent cuckoldry, while females are more sensitive than males to cues of emotional infidelity to prevent loss of parental investment.
The evidence keeps pouring out that gender is not a social construction (as if any reasonable person would think it is).