His parents liking you or not liking you has a lot to do with the impression they perceive from you.
Concerning yourself about whether his parents will like you works against you.
Persisting in this tangent, makes you nervous.
What do we do when we are nervous?
We tighten up and get a little bit uncomfortable.
We are a shell to some extent.
This prevents our personalities from shining through.
Presenting the real you is your winning ticket.
Feel that comfortable with the real you.
Let your personality shine.
Presenting your true self is how they realize who you are and what you are about.
Usually, to impress someone that we so desperately want to impress, we embellish the truth about something or straight out lie.
This is not a good idea.
Being deceptive about something, in the hopes that you gain their approval, only makes their approval very short-lived.
The parents find out that you were being deceptive and this alone puts you in a dreadful position in their eyes.
Be yourself and to be aboveboard.
Do not be afraid to be different or have an opposite view about something.
This is what makes you unique and your own person.
People appreciate opinionated and healthy disagreement.
It makes you appear genuine.
That is the impression you want his parents to have of you.
One of being a genuine person.
When they gather that you are a genuine person, it makes them feel that much more secure in you dating their offspring.
They are more reassured in the perception that your feelings for their offspring must be genuine too.
This is where they trust you.
Once you have gained their trust, you have won them over.
You didn’t have to pretend to be someone that you were not.
To this end, avoid learning too much about his parents before meeting them.
When you ask your partner too many questions about his parents, it makes you more constricted.
Adapting your behavior to what you believe his parents find acceptable, based on what you’ve learned from your partner, contradicts your true self and comes off as fake and rehearsed.
Learning too much information about them works against you.
Go as yourself.
As long as you remain yourself, responding to whatever is asked of you feels effortless and you come off as a lot more authentic to his parents.