Hayward DA, Pomares F, Casey KF, et al. - Researchers used a longitudinal monozygotic (MZ) twin design to ascertain if variations in the prenatal environment [as indexed by discordance in birth weight (BW)] are correlated with resting‐state functional connectivity (rs‐FC) and with structural connectivity. They concentrated on the limbic and default mode networks (DMNs), which are key regions for regulating emotion and the thoughts generated internally. For this analysis, 106 healthy adolescent MZ twins (53 pairs; 42% male pairs) followed longitudinally from birth underwent an MRI session at age 15. According to the results, BW had no associations with the DMN. Such results highlight the potential role of unique prenatal environmental influences, regardless of DNA sequence or shared environment, in the later development of efficient spontaneous limbic network connections within healthy people.