Infant zygosity can be assigned by parental report questionnaire data

Area of Science:

• Twin studies
• Genetics
• Developmental psychology

Background:

• Determining zygosity (the genetic identity of twins) is crucial for twin research.
• Accurate zygosity determination in infancy is essential for longitudinal studies.

Purpose of the Study:

• To validate a parental report questionnaire for determining twin zygosity in 18-month-old infants.
• To assess the reliability of the questionnaire upon re-administration at 3 years of age.

Main Methods:

• A parental report questionnaire was administered to a population sample of 18-month-old twins.
• Zygosity determined by the questionnaire was validated against zygosity determined by polymorphic DNA markers.
• The questionnaire was re-administered to the same children at 3 years of age.

Main Results:

• The questionnaire correctly assigned zygosity in 95% of cases when compared to DNA-based zygosity determination.
• At 3 years of age, 96% of children were assigned the same zygosity on both questionnaire administrations.
• High concordance between questionnaire-based and DNA-based zygosity indicates the method's validity.

Conclusions:

• Parental report questionnaires provide a valid and accurate method for determining twin zygosity in infancy.
• This validated tool can be effectively used in large-scale population studies involving twins.
• The reliability of the questionnaire supports its use for tracking zygosity over early childhood development.