What's a lifetime worth if marriage is the only experience you've had within it? There is that biological difference but whether you make that the lynch pin of your argument - that because they can be pregnant and breast feed, women must therefore be only mothers and wives - depends on what you want in your society. JULIET MITCHELL The average modern family consists of father, mother, and two children living apart from other relations in a separate little box of a house. It's a convenient type of family to have in our industrial and fast-changing society. It can move around from place to place as father changes his job. But is it a happy family? Some experts think it isn't-and millions of women know it isn't. What's the alternative? Do we try to ease things a bit by paying women wages for housework? By sending them to college when their children have grown up? Or do we try something drastic by abolishing housewives altogether, by abolishing husbands, by abolishing the difference in sex roles between men and women? Or do we join men and women in groups with various sexual and living arrangements - ' communes.'? Or do we revolutionise the whole economic and social basis of society as they have in the kibbutzim - the collective settlements of Israel? Commentary spoken by EDGAR WREFORD Executive producer ADRIAN MALONE Produced by DOMINIC FLESSATI