As a home inspector for 27 years and lead paint and lead in water technician I can vouch for the criminal lead paint theory.
Lead causes brain damage in children from birth to about age 5. Lead can be ingested (eaten) or inhaled. Since lead tastes sweet a child will chew wood members such as window sills. Any renovations to a property with lead paint will cause the element to be friable or airborne. One of the main causes of ingestion are kids crawling on floors doused with lead particulate and then sticking their hands in their mouths.
The brain damage is insidious and may or may not have an affect on IQ but certainly has an affect on right and wrong decisions.
This behavior modification can lead to criminal behavior later in life.
Since my Dad was a carpenter and builder he had many exposed sources of lead in our home. All paint was lead based and he painted all metal with “red lead” paint procured from his job at PSEG.
Back in the ‘50's and ‘60's all gasoline was leaded to reduce friction in the cylinders.
The residue of lead was everywhere and those city children got hurt the most from the exposure.
I believe I am a victim of lead paint poisoning and I hope more is researched on this correlation between lead exposure and criminality.
In the meantime I must ask President Donald J Trump for a full and unprejudiced pardon for all my wrongdoings in my wayward misspent youth. For I have been a naughty boy. A very naughty boy!