I agree wholeheartedly with @Jellycatspyjamas in her post above; there is no reason why your children’s therapies and assessments for neurodiversity cannot be simultaneous. As a parent, you can seek referral for assessment from your GP. It is too reductive when the ‘experts’ automatically label everything as attachment difficulties because a child is adopted.
There are very high heritability factors for both ADHD and autism - both in the region of 80 per cent, I believe. It is likely that a big proportion of birth parents who have their children removed have ADHD and/or autism, even if they are undiagnosed, hence the dopamine-seeking behaviours of drinking, drug taking and the ensuing chaotic lifestyles and domestic violence.
The following is from NICE:
The exact cause of attention deficit hyperactivity disorder (ADHD) is unknown but involves the interplay of multiple genetic and environmental factors that are thought to lead to altered brain neurochemistry and structure.
There is substantial evidence for a genetic contribution to ADHD, with a mean heritability of 76% demonstrated in twin studies. It has been hypothesised that several genes may interact to cause ADHD, or that ADHD may be the common phenotype for numerous variant alleles.
Environmental factors most strongly associated with ADHD are low birth weight and maternal smoking during pregnancy. Other risk factors include preterm delivery, epilepsy, acquired brain injury, lead exposure, iron deficiency, alcohol exposure during pregnancy, psychosocial adversity, and adverse maternal mental health.
My DD1 (15) was only diagnosed with ADHD and autism this year; I really wish I had sought assessment sooner but too many therapists (some of them snake-oil merchants) were adamant everything was because ‘attachment’. My DD1 is blind and has autism and ADHD as well as neonatal abstinence syndrome; each of the professionals working with her sees the issue through their own lens of expertise and learned preference whereas, as the parent, I often feel like I’m the only person managing the cumulative mass of ‘stuff’ in the overlapping centre of the Venn diagram.