“The widespread myth in Western contexts that the male breadwinner–female homemaker nuclear family is the ‘traditional’ family structure leads to a focus on mothers alone as the individuals with responsibility for child wellbeing.
Inaccurate perceptions about the family have the potential to distort academic research and public perceptions, and hamper attempts to improve parental and child health.
These perceptions may have arisen partly from academic research in disciplines that focus on the Western middle classes, where this particular family form was idealized in the mid-twentieth century, when many of these disciplines were developing their foundational research.”
https://royalsocietypublishing.org/doi/10.1098/rstb.2020.0020
I don’t know anything about lyndon johnson. but I know the model of nuclear family that was idolized in 1950s and 1960s america – A phenomenon (idolization) that you do NOT see before World War II – Has led to numerous problems in various fields and have had real world negative consequences financially for real families not just in spoiling academic research.