page.php

<?php

add_action( 'genesis_after_header', 'agency_home_welcome_helper' );

function agency_home_welcome_helper() {

    if (has_post_thumbnail( $post->ID ) ) :
        echo get_the_post_thumbnail($post->ID);

    else :

        if ( is_active_sidebar( 'home-slider' ) ) :
            echo '<div id="home-slider">';
            dynamic_sidebar( 'home-slider' );
            echo '</div><!-- end #home-slider -->';

        endif;

    endif;

}

genesis();