I think I had "very feminist" ideas from an early age. I wasn't brought up in a feminist household but my mum is a very intelligent woman, who got divorced soon after having me, and didn't comply with the typical female stereotype.
I remember going to visit my cousins, in a family where the girls had to make the beds and set the table because they were girls while the boys could just play outside because they were boys, and thinking "Gosh, that's so wrong!".
I met my step mum in my early twenties in Spain and she's a real feminist. I think talking to her helped me structure and shape thoughts that I had in me since I was a child.
Then I became a mother, and that made me realise that gender is still a huge issue in society, and how empowered - or disempowered - you will be within that society highly depends on whether you were born a man or a woman.
I'd call myself a feminist any time, but I'm aware that a lot of people/women are not comfortable with the label, so I'm sort of quiet about it. I know that most of my friends share my views, they just don't like calling themselves feminists.
For me it was as simple as having my daughter. I just stopped seeing things the same way. I had my son and realised that feminism is important for him too...and now I have another little girl on the way. I can NEVER understand how people with children are not feminists.
I have found this thread really thought provoking and I could write pages and pages on the reasons I am who I am and that I probably always have been a feminist (in hiding). The fact is that I only started to identify myself as a feminist when my child was born 1.5 years ago, I want a more tolerant open-minded equal world for him to grow up in.