A new study reports associations between birth order and the likelihood of developing certain conditions. According to the report, people who are firstborn or eldest children show a higher likelihood of being diagnosed with autism compared with later-born siblings. The same research also finds that younger siblings have a higher risk of developing addiction-related problems, compared with those born earlier. The article framing describes these patterns as correlations, indicating that birth order may be linked to health outcomes rather than serving as a direct cause. The sources do not provide detailed methods or statistical results in the text provided, but they present the findings as evidence that family birth timing could relate to differences in outcomes across individuals. Overall, the story centers on the idea that genetic or family-environment factors associated with being first or later in a sibling group may correspond to different health risks, including autism for eldest children and addiction for younger siblings.