Edit the header size (css and php) in Genesis.

functions.php

//edit lines 84-89 of functions.php of your genesis parallax theme to your logo's height and width

add_theme_support( 'custom-header', array(
	'width'           => 300,
	'height'          => 70,
	'header-selector' => '.site-title a',
	'header-text'     => false,
) );

header.css

/*set to your logo png or graphic width*/
.title-area {
	width: 300px;
}

/* same as above */
.header-image .site-title > a {
	max-width: 300px;
}