Sexual development and guidance

Hallo,
I'm single, but recently I was at my friends house, she has a daughter and son. Occasionally I notice some sexual impulses in her kids behavior. For example, her daughter (13) was rubbing her pelvis against my friends brother thigh (through some kind of play) and she felt (not orgasm, of course) some kind of body release. Also sometimes I saw my friends son (10) rubbing his pelvis against her mother, during cuddling with her (you know, "mother-son love sparkles").
That family is more 'relaxed' that the one I grew up. I remember that I was so shamed by my parents about sexuality that while all my friends were making sex jokes, I was like 'shame on you' attitude, or 'I'm not interested in sexual things, that's primitive'. One day I only opened my eyes for this subject and acknowledged that was a part of me. Pretty late I lost my virginity. Still I carry a lot of shame from my childhood.
Cause of this, I remembered my childhood and how my older sister was jealous about my Oedipus complex (I never asked her where she heard about it) and it was true.
What I wanted to ask was, since I would like one day, maybe soon, to be a parent, how do you guide these childish sexual behavior and impulses? When I mention something to those kids of my friend something about girlfriend/boyfriend stuff, they are ashamed and they kind of avoid to talk about that subject, they are ashamed of it. Obviously and of course their bodies aren't mature enough for this, but those impulses of their bodies are there.
So, how do you guide this?

it might not have been sexual impluses, but you may have perceived them to be, how do you know she experienced a bodily release? what evidence have you got to suggest this to be true?

The oedipus complex is when a child wants to have sex with a parent, coined by Fraud. My friend is studying for a doctorate in psychology, and uncovered to me some truths about Freud. The fact is that in that day, Freud discovered that a large percentage of his clients had been sexually abused as children, however, the powers that be was shocked and horrified of this finding and threatened to silence and end Freud's career if he ever made this known, so the oedipus complex was created. It is not normal for a child to want to have sex with a parent, however, there are many adults who have warped minds and desire to have sex with a child, not for sexual pleasure, but to control and manipulate children, a sadistic part of them. The oedipus complex makes it out that it is children that are sexually deviant, and possibly to blame for sexual abuse, but it is the other way round. If Freud did his findings in this day and age, that complex wouldn't have even existed.