Christians in America are more likely to say it was their mother's faith that influenced them rather than their father's, although research has found that grandparents are significant too.
The Barna Group study found that mothers were the main drivers of spiritual development in homes, with over two thirds of American Christians (68%) saying their beliefs were influenced by their mother's faith.
This was significantly lower than the proportion (46%) who said their father was the main influencer.
Commenting on the findings, Barna said: "Practising Christians most often credit their parents as the individuals who helped impart faith to them. In this and other responses throughout the study, it appears that spiritual development in the home is driven by mothers."
Older generations were also influential in spiritual development, though, with 37% of the 2,347 adults interviewed crediting their grandparents with shaping their faith, while well over half (59%) said that they grew up to be a Christian in adulthood because a member of the family had "passed down" the faith.
Among those who cited their grandparents, it was grandmothers who were more likely to receive the credit than grandfathers.
People outside the family were far less influential, with only 16% crediting someone who was not a relative, and fewer still (14%) identifying a friend as a significant influence on their faith.
Only 15% said their beliefs as an adult had not been affected by the household they grew up in, while around one in 10 (11%) said "someone explored faith at the same time I did".
More than one in five (23%) said they grew up to be a Christian despite having a negative experience of Christianity during their childhood.
Over half (57%) said they were Christian at the time of their birth, a response that Barna said was "revealing either of their theology or of how extensively Christianity permeated their upbringing".
"For most practising Christian adults in this study, the early, formative days of discipleship occur in their family of origin," Barna said.