Structure influences informal groups because the basis of coming together is often shared interests.
There are several ways in which structure influences informal groups. Informal groups could be seen in project teams, lunch groups, and innovation clubs. The fundamental reason why these groups are formed in the first place would be shared interests or goals.
For example, if a group of employees are not happy about a decision by the management, they may form a lunch group or team to discuss their views and ways to resolve the misunderstandings. So, even if a group is informal in nature, hierarchies may be found between them and shared interests give them structure.