in the family

(all) in the family

restricted to one's own family, as with private or embarrassing information. Don't tell anyone else. Please keep it all in the family. He only told his brother because he wanted it to remain in the family.
See also: family
References in classic literature ?
These questions, then as now, existed only for those who see nothing in marriage but the pleasure married people get from one another, that is, only the beginnings of marriage and not its whole significance, which lies in the family.
Elzbieta had some traditions behind her; she had been a person of importance in her girlhood--had lived on a big estate and had servants, and might have married well and been a lady, but for the fact that there had been nine daughters and no sons in the family.
It had been handed down from father to son; for the singular clause of the only will that had been found, had caused it to be regarded as a genuine relic, preserved in the family with superstitious veneration.
And though he had to be loaded with lands and gold and made an ancestor of dukes, the elf-shaped ear is still recurrent in the family.
Thorpe's interest in the family, by his sister's approaching connection with one of its members, and his own views on another (circumstances of which he boasted with almost equal openness), seemed sufficient vouchers for his truth; and to these were added the absolute facts of the Allens being wealthy and childless, of Miss Morland's being under their care, and -- as soon as his acquaintance allowed him to judge -- of their treating her with parental kindness.
When the war came on it found in the family, as in so many others in that State, a divided sentiment; the young man was loyal to the Union, the others savagely hostile.
But they had; they undoubtedly had; for the low- toned comments behind him left no doubt in Archer's mind that the young woman was May Welland's cousin, the cousin always referred to in the family as "poor Ellen Olenska.
Some had no spare room, some had a larder less well stocked than usual, some had sickness in the family, some were "unequally yoked together with unbelievers" who disliked strange ministers.
Looking at it with my friendly interest in the family, I thought it very remarkable.