I've heard some historians argue that we should not evaluate pederasty according to our contemporary morals, current understanding of healthy childhood development, etc, because the cultural context was entirely different. Some have even gone so far to say that pederasty was fundamental to education of the youth in Athens, and responsible for its success. However, others argue that basic human psychology cannot have changed much over the last few millennia, and the consensus among contemporary psychologists is that sexual contact between adolescent boys and much older men causes lasting trauma, including PTSD. I even read an anecdote of an ancient boy driven to suicide when his "mentor" publicly called attention to sexual acts he did to him.
So my question is: what was the psychological impact of pederasty on boys in ancient Greece?
Note: ideally we'd be able to reference hard facts like x% of boys in the pederastic system suffered from PTSD as adults, the suicide rate increased by y% over boys who were not part of it, etc. Since social sciences were not developed back then, I recognize it is impossible to make such claims. However, I would prefer an answer that at least attempts to answer this question about the population as a whole while taking into account the bias of writers at the time and the bias in what was written down at all, rather than an answer which merely collects a few anecdotes about individuals who did well/poorly later in life. I welcome discussions of methodology!
I have an earlier answer that might interest you:
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As I understand it, explicit concern over the psychological (as opposed to physical) impact of child abuse/sexual abuse is a 20th century development; we have some great history of psych flairs who would be able to tell you more about that. However, this is an interesting question because OP has specifically asked about sexual practices that were not considered abuse in a particular historical context.
Late antique Jewish moral writing, and then derived from that early Greek Christian authors, comes down very harsh on Greek (and later Latin) institutionalized traditions of pederasty/pedophilia (paiderasteō). The idea of corruption of the boys involved runs deep.
Philo of Alexandria, De specialibus legibus III.37-42, explains:
Moreover, another evil, much greater than that which we have already mentioned, has made its way among and been let loose upon cities, namely, the love of boys, which formerly was accounted a great infamy even to be spoken of, but which sin is a subject of boasting not only to those who practise it, but even to those who suffer it, and who, being accustomed to bearing the affliction of being treated like women, waste away as to both their souls and bodies, not bearing about them a single spark of a manly character to be kindled into a flame
Philo's specific criticism is that being the victim of Greek pederasty makes boys accept and want the practice. In another text, De contemplativa vita, he more obliquely criticizes how pederasts use and discard the youngest boys.
Following this line of corruption, early Greek Christian texts will introduce the word paidophthoreō to label the same practice. But rather than the eros/carnal love connotations of paiderasteō, John Martens argues, paidophthoreō invokes a web of meaning of destroy or corrupt. The Didache, a very early Christian text, places paidophthoreō as a crime next to infanticide: the utter destruction of children.
Some sensitivity is mandated here. Philo's criticism, after all, is that the victims of pederasty (he uses the older Greek term, although he condemns the practice; there is only one Jewish source that uses paidophthoreō) grow up to be too feminine, and heavens forbid we should accept ancient and medieval ideas of gender boundaries as trans-historical, Platonic ideals. I'm not comfortable with the idea of wholesale dismissing gender performance as 100% the result of sexual abuse, no question, move along.
However, I think there is a good argument to be made based on contemporary and later traditions that the idea of dealing with sexual abuse/pedophilia by striving to accommodate it, mentally, was implicitly and obliquely recognized by late antique and medieval authors. I'm no psychologist and it's important to remember that the modern idea of psychology, mental illnesses, and even emotions are culturally constructed, but it seems to be that modern research finds some resonance in this idea.
So I want to turn to a different type of case, fictional narratives of incest. Medieval sources really don't like to discuss sexual abuse of children directly, but as Kathryn Gravdal points out, incest stories present a way around or through the silence by keeping the focus elsewhere. She differentiates between "canonical incest," or degrees of consanguinity for marriage purposes, and incest within the nuclear family. Specifically, we have stories of mother-son and father-daughter incest which are, always, turned towards an ultimately didactic purpose. What I want to highlight here are the very different standard portrayals of those types of incest in hagiographies, narrative poems, and exempla (moral lessons).
The prototypical mother-son incest story is, I would argue, the heir of the "corruption" critique. In these, the mother is a new widow who sees in her child the spitting image of her dead husband. She initiates the sexually abusive relationship; the boy grows up to fall in love with her. Again, the idea of aligning oneself/accepting the situation as a way to deal, cognitively, finds resonance both in Philo's writing and in modern research.
The stories of father-daughter incest are very different, certainly also reflecting gender norms. Here, the father is portrayed as a predator. As with stories of saintly women fleeing arranged marriages, the girls disfigure themselves--even to the point of amputating a hand--and flee their homes. The stories recount their suffering and hardships in the world. These are external consequences, of course, not "internal" ones--don't expect to find long descriptions of PTSD-type nightmares or flashbacks. However, these texts (unlike the saints who disfigure themselves to flee marriage, who usually wind up martyred) generally have more upbeat endings. The daughters, after massive suffering, will often wind their way to a husband and children of their own. There is room to see, given the medieval refusal to confront certain subjects directly, these stories as a sort of externalization of internal processes. (A literary topos that medieval writers loved.)
Incest is a different case than institutionalized pederasty or early marriage, obviously. However, the parallels between the father-daughter incest narratives and the standard flight from early marriage stories are a really striking overlap that, I argue, justifies an extrapolation from specifically incest to forced sexual activity as a child in other circumstances as well.
So with all the care and sensitivity needed to reconstruct premodern emotions, psychology, and sexual norms, plus some careful reading of and through sources, I would argue that we can see both the emotional effects of childhood sexual abuse and an implicit, oblique awareness of them.