And oh yes, since scouting tends to be a family thing where if one son is enrolled in Boy Scouts, the other sons will be too, that means any supposed causal effect of Boy Scouts would fall under 'shared environment' estimates from family & twin designs, which measure the influence of all variables influencing entire families such as parenting choices. And shared environment estimates for anxiety and mental health disorders in general are almost always small. So... if taken at face value, the choice of Boy Scouting or not could explain most or all of a family's influence on anxiety! This seems highly improbable, to say the least.