An analysis of online posts suggests that men are more likely to regret missed sexual opportunities while women are more likely to regret engaging in sex and romantic relationships.

The new research, published in Evolutionary Behavioral Sciences, supports the theory that sexual regret functions differently in men and women due to asymmetries in parental investment. While a woman might face nine months of a metabolically-costly pregnancy after having sex, the minimal obligatory investment for a man is almost zero.

The new study consisted of two parts. In the first, the researchers analyzed 61,412 posts from Craigslist’s missed connections section, where people seek to connect with someone they saw briefly in public. In the second, the researchers collected and examined 3,500 posts from FMyLife.com’s love and intimacy sections, where people anonymously post embarrassing confessionals.

The researchers found that most of the missed connections posts were written by men. There were 42,911 men seeking-women posts but only 18,501 women-seeking-men posts. When it came to embarrassing confessionals regarding love and intimacy, however, the researchers found that women had written more posts than men.