Uncomfortable Idea: If you are past your mid-twenties and engaging in sexual activity with people younger than their mid-twenties, you are likley, knowingly or not, taking advantage of him or her.
Thanks to modern research in the area of neuroscience, we now know that the human brain, specifically the prefrontal cortex which is the area responsible for executive function such as decision making, does not fully mature until the person's mid-twenties (Arain et al., 2013). From a moral standpoint, we agree that having sexual relations with young people who are not fully sexually developed is wrong, so why is it acceptable to have sexual relations with young people who are not fully cognitively developed? Of course, cognitive development is not a binary event where at some magical age one becomes "fully cognitively developed," and we don't know at what point is the minimum cognitive development necessary to make life decisions such as having sex with someone that can lead to pregnancy or STDs. Some people develop cognitively faster than others, and some people never fully develop cognitively. There are no hard rules here, just that if morality is a concern to us, we shouldn't just be using the age of consent laws as a guide for acceptable sexual relationships, but rather look at what science tells us about cognitive development, and use that age range instead.
{apa}References
Arain, M., Haque, M., Johal, L., Mathur, P., Nel, W., Rais, A., … Sharma, S. (2013). Maturation of the adolescent brain. Neuropsychiatric Disease and Treatment, 9, 449–461. https://doi.org/10.2147/NDT.S39776{/apa}