Are all babies born with ADHD features, and only those who don't outgrow it become diagnosed as adhd?

Wow. Adhd is an inherited neurobiologic disorder of executive brain function. It's there at conception, worsened by prenatal nicotine, alcohol, drug or marijuana exposure. Worsened by premature birth (<38 weeks) distressed birth or neonatal stress. The features of adhd require the ability to assess executive brain function so the patient needs to be at least 4 yo for an accurate diagnosis.
No. Adhd, add, tourette and various degrees of behavior are all abnormally acquired. My hard won experience in practice over 54 years has proved to me that the all too common standard american diet (sad) and the free use of sugar, pop, ice cream etc. Is a major cause affecting millions of our children. Add to that industrial pollution and you have a nightmare situation.