I think knocking left handed behavouir out of kidswas pretty general and not limited to nuns. My sister and I were left handed. She was a boarder at a chairty run girls school and I went to a normal state run day school and both of us were forced to go right handed which more than 50 years on does not feel natural to us. Churches and especially the Roman Catholic church seek to bind their members to them. The techniques they employ are many and various but bear little to the teaching of Jesus ( who I believe was influenced by Buddhist philosophy , which was quite possible as he lived on the "slik road" from the East). Relgions are human constructs which at times display both the best and worst of humanity. Organised religions are best avoided. Whatever I believe I keep to myself.

Here the abuse of nun is infamous in the residential school where First Nations children were sent to de-Indian them, many they de-Indianed them to death.