The PEARL-AGE Study. Multigenerational Gut Bacteria Transmission and Its Stability in Families.

Inclusion Criteria: * The following relations of the PEARL mother/baby are eligible for inclusion: * Husband/partner of a PEARL mother, their biological parents and grandparents. * PEARL mother's biological parents and grandparents (great-grandparents to the PEARL baby). * Co-habiting non-biological fathers of the baby such as stepfathers and partners of the PEARL mother, their parents and grandparents. * A biological sibling of the PEARL baby or a step-sibling who is currently co-habiting with the PEARL baby. * Adult participants must be able to consent for themselves and able to understand the questionnaire. * Child participants must have a parent and/or guardian to provide assent on their behalf. * Must be living in England. * Must be willing to accommodate a small cool box to store and transport the biological samples until they are collected, if not having immediate access to the PEARL study freezer. * Vulnerable participants such as participants with mild cognitive impairment may be included as long as they have full support from their family members. Exclusion Criteria: * Not related/affiliated to a mother currently participating in the PEARL study, or the cohabiting partner, or father of the PEARL infant. If a PEARL participant has withdrawn from the PEARL study or is no longer participating, investigators will not approach the PEARL participant for recruitment of their family members. * Step-fathers or long-term partners that have been cohabiting with the…