The rifts between mothers and their sons' wives have been found to be a major cause of family feuds, say researchers.
According to Newcastle University lecturer preparing a PhD study into family disputes Kylie Agllias, the tensions between the two affect family relationships for years.
Other major trouble triggers for conflicting families are messy divorces and parents refusing to lend children money.
She said conservative estimates are that one in 25 parents are estranged from an adult child.
In the first stage of her study, Agallias analysed the estranged family relationships of 25 men and women aged between 60 and 80.
A majority were found to have no contact with their children - as many as seven in some cases - for decades.
However, some have had limited but unsatisfactory contact with family members they felt detached from.
Some of them haven't seen their loved ones for 20, 30 and even 40 years.
Agllias said some of the mothers who didn't get along with their daughters-in-law were in the emotionally estranged category, so they saw their son and his partner, but contact was infrequent and often very uncomfortable.
"What the literature suggests is that the new party may bring in new values, ideas and practices that do not fit with the son's nuclear family," the Daily Telegraph quoted her as saying.
"Some women repeated the saying, 'A daughter is a daughter all your life; a son is a son until he takes a wife'.
"They expected the relationship to change when a new woman joined the family, although none of them expected it to change so dramatically - for example by a physical or emotional estrangement," she added.
Money, new relationships and conflicting belief systems are the source of many ongoing feuds.
"Choice was one of the primary causes. If there'd been a divorce between mum and dad, the young person may decide they can't be friends with both, so estranges one.
"Also, a choice (was made) between the new family when the adult male child married and decided that for some reason he couldn't sustain a relationship with his parental family and have his new nuclear family.
She said others put estrangement down to being punished for something the child perceived that they had done.
"An example would be someone would ring up and ask the parent for a loan or they wanted some of their inheritance early and the parent would say, 'I can't do that, I'm on the pension', and the child would simply say, 'Well, I'm not talking to you any more'," Agllias added.