Twin studies confirm genetic insights

Our twin studies estimate how much genetics influence traits like height, body mass index (BMI), personality, and asthma risk. Traditionally, this is done by comparing identical (MZ) and non-identical (DZ) twins to calculate “heritability” – a measure from zero (no genetic influence) to one (completely genetic).

Critics argue twins aren’t representative of the general population, but new research proves otherwise.

QIMR Berghofer and UQ developed a method that doesn’t rely on MZ twin, Instead, it uses genome-wide data from siblings, who share about 50 percent of their genes (with variation from 42 per cent to 58 per cent). This approach requires huge samples – our recent international collaboration included 120,000 sibling pairs, with QIMR Berghofer contributing 13,000.

The study found:

• Heritability for height: 80 per cent (same as traditional twin estimates)
• Heritability for BMI: 55 per cent (matching twin estimates)
• Family environment: negligible impact

This validates the classic twin method and shows genetics play a major role in these traits.

Further, genome sequencing studies now confirm that the same heritability estimates hold when analysing all 3.1 billion bases of DNA. This means twin studies remain a reliable guide to understanding genetic variation.

Multiple independent methods agree – our genetic blueprint strongly shapes traits like height and BMI, and twin studies remain a cornerstone of genetic research.