The model may have predictive value in a population without explaining or predicting a particular individual's cancer. After all, breast cancer existed before abortion became so prevalent; there is an underlying rate of these cancers within our populations. It is also possible that all the women you know who have had breast cancer haven't told you their abortion histories. It's not a typical topic of conversation, at least among my women friends. Statistically, I'm sure I know women who have had abortions, but I've never had a conversation where it's been admitted to me.
They could have, I doubt it but they could have, yes. One was forced by her father to put her baby up for adoption when she was a teenager (back in the 50s). She never had any others, and she was against abortion. Two others were my great aunts, one who died in the 50s and one who had a mastectomy at age 80 a few years ago.
How do they know then, that the women in the study who say they never had an abortion are telling the truth?