DNA family tree: who is the grandmother, mother, and daughter?

[leoflc]

Homework Statement

By running a DNA blast, we need to identify who is the grandmother, mother, and daughter. And how/why do we know their relationship.

The tree is attached.

Homework Equations

Here are some of the results from blast, I'm not sure if they will help:
Group 1: Sequences: 2 Score:7298
Group 2: Sequences: 2 Score:7245
Group 3: Sequences: 3 Score:7127
Group 4: Sequences: 4 Score:7118
Group 5: Sequences: 2 Score:7448
Group 6: Sequences: 3 Score:7448
Group 7: Sequences: 4 Score:7354
Group 8: Sequences: 8 Score:7075
Group 9: Sequences: 10 Score:7108
Group 10: Sequences: 11 Score:7029
Group 11: Sequences: 12 Score:6977

The Attempt at a Solution

Just by looking at the tree, my guess will be 4 is the grandmother, 6 is the mother, and either 9 or 13 is the daughter. However, I can't justify it.
Where should I look?

Any help is appreciated.

Thank you all.

 

[Moonbear]

I don't know enough about this method to help you all the way through the problem, but one thing to keep in mind is that the distance between any two individuals in the tree indicates their relative relatedness. In other words, if the line connecting two individuals is very short, they are closely related, and if it's very long, they are very distantly related.

As an example, 5 and 11 are very closely related, while 5 and 8 are more distantly related.