Those interested in the family backgrounds of delinquents have paid a good deal of attention to family size and position in family (see Mannheim, 1965, for a review), but little to the ratio of brothers to sisters. This is surprising, since it can be argued that boys who come from families with a preponderance of brothers may be particularly at risk of delinquency; for example, their parents might find it difficult to control them; they might be more likely to play out on the streets and thus have greater opportunities for delinquency; and, since delinquency is a predominantly male activity, they might have a greater chance of being set a bad example through the behaviour of their brothers.