It is wrong to claim that ADHD is exclusively hereditary. Also, epigenetics show that behavior changes what is inherited. This is a chance and a responsibility. [1]

More broadly speaking, anything that is claimed to be "hereditary" (which for ADHD the scientific consensus is that it is not exclusively but estimated at around 70%) could also be early nuture and prenatal environment. The way genetic inheritance is researched (identical twins vs. fraternal twins) cannot account for this. [2]

[1] e.g.

"ADHD has been clearly linked with numerous environmental risk factors, particularly around the prenatal and perinatal period. Some of the most robust risk factors identified are maternal prenatal health conditions and psychological distress (e.g. hypertension, obesity, pre-eclampsia, immune activation), in utero exposure to poor diet (with critical factors still being determined), teratogenic effects of certain medications (e.g. acetaminophen) and environmental exposures (e.g. lead), as well as neonatal factors such as prematurity and low birth weight [27]. Other extreme exposures in the postnatal environment (such as extreme infant emotional neglect) have also been associated with an ADHD syndrome [28, 29]."

Cecil, C. A. M., & Nigg, J. T. (2022). Epigenetics and ADHD: Reflections on Current Knowledge, Research Priorities and Translational Potential. Molecular diagnosis & therapy, 26(6), 581–606. https://doi.org/10.1007/s40291-022-00609-y

"The convincing evidence for genes as risk factors for ADHD does not exclude the environment as a source of etiology. The fact that twin estimates of heritability are less than 100% asserts quite strongly that environmental factors must be involved. ADHD’s heritability is high, and that estimate encompasses gene by environment interaction. Thus, it is possible that such interactions will account for much of ADHD’s etiology. Environmental risk factors likely work through epigenetic mechanisms, which have barely been studied in ADHD [148]. The importance of the environment can also be seen in the fact that, as for other complex genetic disorders, much of ADHD’s heritability is explained by SNPs in regulatory regions rather than coding regions [149]."

Faraone, S. V., & Larsson, H. (2019). Genetics of attention deficit hyperactivity disorder. Molecular psychiatry, 24(4), 562–575. https://doi.org/10.1038/s41380-018-0070-0

"Parental stress and parental depression were significantly associated with increased risk for ADHD overall and both symptoms and diagnosis. Specifically, maternal stress and anxiety, maternal prenatal stress, maternal depression, maternal post-partum depression, and paternal depression were positively associated with ADHD. In addition, parental depression was associated with symptoms of ADHD inattentive and hyperactive/impulsive subtypes. Parental antisocial personality disorder was also positively associated with ADHD overall and specifically ADHD diagnosis. Prenatal antidepressant usage was associated with ADHD when measured dichotomously only. These findings raise the possibility that prevention strategies promoting parental mental health and addressing parental stress could have the potential for positive long-term impacts on child health, well-being, and behavioral outcomes."

Robinson, L. R., Bitsko, R. H., O'Masta, B., Holbrook, J. R., Ko, J., Barry, C. M., Maher, B., Cerles, A., Saadeh, K., MacMillan, L., Mahmooth, Z., Bloomfield, J., Rush, M., & Kaminski, J. W. (2024). A Systematic Review and Meta-analysis of Parental Depression, Antidepressant Usage, Antisocial Personality Disorder, and Stress and Anxiety as Risk Factors for Attention-Deficit/Hyperactivity Disorder (ADHD) in Children. Prevention science : the official journal of the Society for Prevention Research, 25(Suppl 2), 272–290. https://doi.org/10.1007/s11121-022-01383-3

[2]

"twin studies fail to separate the effects of genes and the prenatal environment. This failure casts doubt on claims of the relative effects of genes and environment on intelligence, psychiatric disorders, personality and other psychological variables, and other conditions."

https://www.psychologytoday.com/gb/blog/looking-in-the-cultu...

"Although many twin studies have been conducted (which is quite an understatement; there are almost 9,000 hits for “twin study” on PubMed!), there have long been critics who argue that they are scientifically worthless."

Smith, Jinkinson. (2020). The debate over twin studies: an overview. http://dx.doi.org/10.22541/au.159674847.78026661

"Because heritability is defined by both genetic and environmental influences, it is not a fixed characteristic of a disease or trait, but a population-specific estimate, analogous to, for example, the mean height, cholesterol level or life expectancy in a population. It also cannot be interpretated at the family or individual level."

Kaprio J. (2012). Twins and the mystery of missing heritability: the contribution of gene-environment interactions. Journal of internal medicine, 272(5), 440–448. https://doi.org/10.1111/j.1365-2796.2012.02587.x

More: https://en.wikipedia.org/wiki/Twin_study#Criticism