Note that this Connection Finder includes relationships through marriage. To find blood relations, use the Relationship Finder instead.
As has been explained, the connection finder does the connections thing - using family, marriages, step parents, siblings, etc. The connection finder does not use JUST blood relationships.
If it turns out that the two profiles are related then yes that will show up - but that does not happen every time.
The only line about any blood connection is the one I pasted above - and that is just for the Relationship Finder.
I cannot see any place on the connection finder that specifically says to "request" blood relationship!!
If you are talking about the tab that says "Alternative view: generational path" that also shows only the connections - and again these connections can be by blood and also through marriages and step parents and siblings.