I have a simple question about database desing...

Let's say we have `Table Customer` with some fields: 

```
(PK) Id, 
Firstname, 
Lastname, 
Address, 
City, 
(FK) Sex_Id...

```

So... 

Would it be a good idea to have an additional table `Table Sex` where data about Sex ('M', 'W') would be saved?

```
Sex_Id,
Value

```

or should `Sex` values ('M' or 'W') be saved directly into table `Customer`? What about query speed etc.?

Thanks in advance,
best Regards.