Learning is not just mental process that changes the arrangement of neurons. It can cause epigenetic changes. Inflammation persisting up to adulthood might be learned from example. They may be mitotically and/or meiotically heritable at least to some degree.
During brain development synaptic pruning takes place. Huge part of child's brain just dies out. If the child has this process accelerated due to hardships, or is in the environment not stimulating enough to help brain to decide which neurons to kill ... it's just horrible to think about.
https://onlinelibrary.wiley.com/doi/full/10.1002/dvdy.24211