I'd change it to "My dad is 50 years old." However many people leave Dad capitalized.
It is not acceptable to be unable to use acceptable in a sentence.
Dads aggrandize their money.
Dads aggrandize their money.
The compromise was found acceptable by both sides.
Plagiarism is not acceptable and will be severely penalized.
Using a gerund at the beginning of a sentence is perfectly acceptable.
The sentence is acceptable.
The little girl plowed her dads garden.
Example sentence - The omission of the facts was not acceptable to the grand jury.
It is acceptable that an adult drink a cup of red wine everyday.
The stubbles on my dads face were very scratchy.
The acceptable ozone is 300 to 50 Dobson unit. It is present in the stratosphere.