Bertrand Russell, answered from the texts and cited to the page.
Sexual morality should be founded on the welfare of children and on the avoidance of jealousy and cruelty rather than on the taboos of an ascetic tradition. Adultery need not dissolve a marriage; sexual knowledge should not be withheld from the young.1234
It is a mistake to begin with the loves of the bees and the flowers; there is no point in leading up to the facts of life by devious routes. The child who is told what he wants to know, and allowed to see his parents naked, will have no pruriency and no obsession of a sexual kind.10. Our Sexual Ethics, pp. 109–110
No doubt convention determines, in a given community, exactly what is to be considered indecent, but the universal existence of some convention of a kind is conclusive evidence of a source which is not merely conventional. In almost every human society, pornography and exhibitionism are reckoned as offences, except when, as not infrequently occurs, they form part of religious ceremonies.10. Our Sexual Ethics, pp. 106–107
The law declares bluntly that children and young people must not know the facts of sex, and that the question whether it is good or bad for them to know these facts is entirely irrelevant.Marriage and Morals
None of them condemn the brutality of a husband who causes his wife to die of too frequent pregnancies. I knew a fashionable clergyman whose wife had nine children in nine years. The doctors told him that if she had another she would die. Next year she had another and died. No one condemned him; he retained his benefice, and married again.What I Believe
The book that cost him a chair in New York, and the one his biographers use to convict him of hypocrisy.