Q:

How to correctly use conditionals like IF or CASE in Cypher query language (Neo4J) to successfully create relationships?

I failed to create relationships in Neo4J and I would like to encourage anyone who has sucessfully done it to help me.
The desired result is to have a detailed visualisation of who is a brother to whom, who is who's mother and so on. I want to extract the data from single parent-child relationships. That means, setting a relationship like [:relatedTo {:how['daughter']}] if a node has a parent whose name corresponds to the field node.name and the gender of the node is F.
I have my CSV file that looks like this.
1;Jakub Hančin;M;1994;4;3
2;Hana Hančinová;F;1991;4;3
3;Alojz Hančin jr.;M;1968;15;14
4;Viera Hančinová;F;1968;9;
5;Miroslav Barus sr.;M;1965;9;
6;Helena Barusová;F;1942;;
7;Miroslav Barus jr.;M;1995;6;5
8;Martin Barus;M;1991;6;5
9;Hedviga Barusová;F;1945;;
10;Peter Hančin jr.;M;1991;12;13
11;Zuzka Hančinová;F;1996;12;13
12;Andrea Hančinová;F;1966;;
13;Peter Hančin sr.;M;1965;15;14
14;Alojz Hančin sr.;M;1937;;
15;Anna Hančinová;F;1945;;

This is my personal family tree and I would like to visualize it through Neo4J.
It is a file created with Excel, where I put the information into a table and create a database. Then it was converted to .csv file which is importable into Neo4J. I have sucessfully installed it and now I am at the point of writing the Cypher script to manage it. So far, I have this:
LOAD CSV WITH HEADERS FROM "file:c:/users/Skelo/Desktop/Family Database/Family Database CSV UTF.txt" AS row FIELDTERMINATOR ';'
CREATE (n:Person)
SET n = row, n.name = row.name,
  n.personID = toInt(row.personID) , n.G = row.G,
  n.Year = toInt(row.Year), n.Parent1 = row.Parent1, n.Parent2 = row.Parent2
WITH n

MATCH(n:Person),(b:Person)
WHERE n.Parent1 = b.name OR n.Parent2 = b.name

CASE b.gender
WHEN b.gender = 'F' THEN
CREATE (b)-[:isRelatedTo{how:['mother']}]->(n)
WHEN b.gender = 'M' THEN
CREATE (b)-[:isRelatedTo{how:['father']}]->(n)
RETURN *

The error message shown looks like this.
Invalid input 'A': expected 'r/R' (line 11, column 2 (offset: 389))
"CASE b.gender"
  ^

Somehow, I can't figure out why this does not work. Why can't I use the Case command? The Neo4J does not allow me to use anything but the command CREATE (it expects a letter R after C and not an A, this means the CREATE command).
Again, I want to do this. I have a few nodes that are correctly set. For each of those nodes (they represent people), I want to look into the Parent1 and Parent2 fields and to look for a node that has the same name as one of these fields. If it matches one of these, I want to mark that node as a father or a mother to the previous node (judging by the gender of the node, which represents the person).
This way I would like to fill the graph database with many relationships, but I fail at this very basic step. Please help me. If you can, please do not only say what is wrong and why it is wrong, but present a solution that works. 

A:

Since you want to create the isRelatedTo relationship regardless of gender and only the property is dependent upon a conditional, do this:
CREATE (b)-[r:isRelatedTo]->(n)
SET r.how = CASE b.gender WHEN 'F' THEN 'mother' ELSE 'father' END

