Sister advice

So I have a question for everyone who's willing to help. My sister came to me for advice but I feel like I can't really help her & I asked her if it would be okay for me to ask all the lady's on here & she agreed. She says that everytime her & her husband are intimate he ALWAYS wants to go anal. He's not really interested in her lady part & she's wondering if it's normal for a man to be asking for anal all the time. Thanks for the help in advanced