Last version of Genesis 1.8.1 (even has got its own SEO options) they mentioned that this version can be easily integrated with "SEO by Yoast" SEO plugin. This is little strange if you know that genesis framework has integrated their own SEO options. This showing me that Joost's plugin is more advanced and second that Genesis is great platform and the developer team brings the best for their clients.
And now back to the question.
1. Is there any need to modify the titles in header.php ?
2. If Yes How to do it when you are using child theme?