Voted no, but I also don't think that 'consent' is just a matter of physically saying 'yes' or 'no'. The law agrees with me - which is why no amount of attempted consent prevents sex by an adult with an underage teenager/kid from being rape.
Firstly, consent requires an understanding of the likely repercussions of the activity. It isn't enough, for example, to know what sex is and how to do it. The person also has to be capable of understanding how pregnancy or STDs are likely to affect his future goals/lifestyle, and must be capable of placing any risks in that context. The person needs to be capable of working out how they are likely to be affected emotionally. Most victims of paedophilia don't view the activity as wrong UNTIL they are well into adulthood, often a couple of decades after the events. The paedophile has no grounds to complain, because the victim's delay is EXACTLY what you'd expect - i.e. they weren't capable of fully understanding the ramifications and context of a sexual relationship at the time, and they didn't realise how they were being taken advantage of, nullifying their consent. The fact that they only came to this conclusion after the events just serves to emphasise why we rule that kids/teenagers aren't capable of consenting (if nothing else, society needs certainty - need to have the age of consent at an age where people aren't likely to change their mind 10 years after the event).
Consent ALSO needs to be free from gross power imbalances. That's why incest, even between adults, is almost always wrong. Families have inbuilt power structures that are enormously strong. You rely on each other for the basics of being raised, for co-raising each others' children, for financial, emotional and practical support. In those circumstances, there is a real danger that an apparent 'consent' will actually be marred by one partner having near-absolute control over the other. There are plenty of cases of children who have been molested by a parent, where the molestation continued past the age of 18. Usually, the sex wasn't physically resisted, and would have all the appearances and 'not nows', and 'okay nows' of a consensual relationship. But the problem is that neither partner can actually choose to not have a relationship with the other. They are already in an intimate relationship by virtue of being father and daughter (or son). With a sexual element added into it, you've got a person who is essentially trapped. They fear that if they say no, there's going to be violence, or that it's their father and they CAN'T say no (having been conditioned that was as a child). They worry that their mother/family will blame them, and so they go along with it to prevent others from finding out. They worry that a police investigation/prosecution will tear the family apart, and everyone will blame them for sending the father to jail. Or they might just not want to send their father to jail, even if they don't want to have sex with him. Same thing can occur with brother/sister.
Hence most incest, even between adults, is wrong because they can't give meaningful consent, only formal consent. Same with relationships where one person controls the other through physical or extreme emotional abuse.