Thank you for posting another thought-provoking article. This sentence may be key:
Quote
Most parents appear to be ineffective at helping their children with homework.
Extrapolated to other areas, including reading to or with a child, and discussing school experiences... the level of expertise or effectiveness of the parents may have a strong positive or negative effect.

This brings to mind the work of Hart & Risley.

Having positive interactions with children such as two-way conversations (as opposed to directives) was a distinction observed by Hart&Risely.

Some parents may find spanking to be a culturally acceptable form of discipline. The impact of a spanking parent "regularly discussing school experiences" may have a negative impact on a child's self-esteem and performance.

Some may say that the ethnic groups whose children were seen to benefit most from parental involvement may be characterized by:
- developing a network for acquiring information/support for parents
- sharing information freely among one's cultural group
- positive, supportive interactions with their children.

LOL, this does not account for helicopter parents or hothousing Tiger Moms who tend to be competitive, pushy, and may guard opportunities/information from others.