Family, ethics and the

2. Biological conceptions of families

On a biological view, family ties are defined primarily through reproductive and genetic links. We distinguish between ‘real’ or ‘true’ mothers and adoptive, ‘social’ or step-mothers, full brothers and half-brothers, first cousins and distant cousins. Such traditional distinctions are accompanied by different levels of priority within families: the saying that ‘blood is thicker than water’ (and than diluted blood) indicates that blood kin have greater obligations to one another than to other relatives, but presumably find those greater demands less onerous in virtue of a natural sympathy that sociobiologists attribute to gene-preserving strategies (see Sociobiology).

However enshrined in legal and moral sentiment, this biological-based approach has problems of gradation, derivation and scope. Whatever genetic links or tendencies, do we owe half-sisters less loyal support? Do adoptive parents have more excuse for failing in their parental duties of care and comfort? Do adopted children have less obligation to ‘honour’ their parents, or more? If the moral gradations set out in such questions are indefensible, it would seem that an appeal to more than Darwinian notions would be needed to bridge Hume’s gap between is and ought (see Logic of ethical discourse §§1–3).

But even if such prescriptive norms for family composition and conduct can be drawn from evolutionary or any other biological theory, there is an issue of scope. Whatever the value ascribed to biological connections, they are only a fraction of the ties by which families are formed and maintained. Biological considerations may govern marital and reproductive choices but have little or no bearing on many other family obligations, such as those of parents to their in-laws, or to one another, or to their children once they have become adult (grandchildren aside). Non-biological bases must be found for these other familial ties.