Why do some people wish to restrict access to their DNA sequence

The major reason for people restricting access to their DNA sequence is "privacy".

Explanation:

First of all, we need to understand something, people believe that they can know their DNA sequence without any problem. However, they think very differently about sharing it with more people than themselves or their closed ones. Because they believe its private. Thus, the majority of the reasons are because they believe they and their closed ones are the only people that have the right to know it.